Static multiview display and method

ABSTRACT

A static multiview display and method of static multiview display operation provide a static multiview image using diffractive gratings to diffractively scatter light from guided light beams having different radial directions. The static multiview display includes a light guide configured to guide plurality of guided light beams and a light source configured to provide the guided light beam plurality having the different radial directions. The static multiview display further includes a plurality of diffraction gratings configured to provide from a portion of the guided light beams directional light beams having intensities and principal angular directions corresponding to view pixels of the static multiview image.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation patent application of and claims thebenefit of priority to International Application No. PCT/US2017/053817,filed Sep. 27, 2017, which claims priority to U.S. Provisional PatentApplication Ser. No. 62/442,982, filed Jan. 6, 2017, the entire contentsof which are incorporated by reference herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

N/A

BACKGROUND

Displays and more particularly ‘electronic’ displays are a nearlyubiquitous medium for communicating information to users of a widevariety of devices and products. For example, electronic displays may befound in various devices and applications including, but not limited to,mobile telephones (e.g., smart phones), watches, tablet computes, mobilecomputers (e.g., laptop computers), personal computers and computermonitors, automobile display consoles, camera displays, and variousother mobile as well as substantially non-mobile display applicationsand devices. Electronic displays generally employ a differential patternof pixel intensity to represent or display an image or similarinformation that is being communicated. The differential pixel intensitypattern may be provided by reflecting light incident on the display asin the case of passive electronic displays. Alternatively, theelectronic display may provide or emit light to provide the differentialpixel intensity pattern. Electronic displays that emit light are oftenreferred to as active displays.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features of examples and embodiments in accordance with theprinciples described herein may be more readily understood withreference to the following detailed description taken in conjunctionwith the accompanying drawings, where like reference numerals designatelike structural elements, and in which:

FIG. 1A illustrates a perspective view of a multiview display in anexample, according to an embodiment consistent with the principlesdescribed herein.

FIG. 1B illustrates a graphical representation of angular components ofa light beam having a particular principal angular directioncorresponding to a view direction of a multiview display in an example,according to an embodiment consistent with the principles describedherein.

FIG. 2 illustrates a cross-sectional view of a diffraction grating in anexample, according to an embodiment consistent with the principlesdescribed herein.

FIG. 3A illustrates a plan view of a static multiview display in anexample, according to an embodiment consistent with the principlesdescribed herein.

FIG. 3B illustrates a cross-sectional view of a portion of a staticmultiview display in an example, according to an embodiment consistentwith the principles described herein.

FIG. 3C illustrates a perspective view of a static multiview display inan example, according to an embodiment consistent with the principlesdescribed herein.

FIG. 4 illustrates a plan view of a static multiview display in anexample, according to an embodiment consistent with the principlesdescribed herein.

FIG. 5A illustrates a plan view of a static multiview display includingspurious reflection mitigation in an example, according to an embodimentconsistent with the principles described herein.

FIG. 5B illustrates a plan view of a static multiview display includingspurious reflection mitigation in an example, according to anotherembodiment consistent with the principles described herein.

FIG. 6A illustrates a plan view of a multiview display in an example,according to an embodiment consistent with the principles describedherein.

FIG. 6B illustrates a plan view of the static multiview display of FIG.6A in another example, according to an embodiment consistent with theprinciples described herein.

FIG. 7A illustrates a plan view of a diffraction grating of a multiviewdisplay in an example, according to an embodiment consistent with theprinciples described herein.

FIG. 7B illustrates a plan view of a set diffraction gratings organizedas a multiview pixel in an example, according to another embodimentconsistent with the principles described herein.

FIG. 8 illustrates a block diagram of a static multiview display in anexample, according to an embodiment consistent with the principlesdescribed herein.

FIG. 9 illustrates a flow chart of a method of static multiview displayoperation in an example, according to an embodiment consistent with theprinciples described herein.

Certain examples and embodiments have other features that are one of inaddition to and in lieu of the features illustrated in theabove-referenced figures. These and other features are detailed belowwith reference to the above-referenced figures.

DETAILED DESCRIPTION

Examples and embodiments in accordance with the principles describedherein provide display of a static or quasi-static three-dimensional(3D) or multiview image. In particular, embodiments consistent with theprinciples described display the static or quasi-static multiview imageusing a plurality of directional light beams. The individual intensitiesand directions of directional light beams of the directional light beamplurality, in turn, correspond to various view pixels in views of themultiview image being displayed. According to various embodiments, theindividual intensities and, in some embodiments, the individualdirections of the directional light beams are predetermined or ‘fixed.’As such, the displayed multiview image may be referred to as a static orquasi-static multiview image.

According to various embodiments, a static multiview display configuredto display the static or quasi-static multiview image comprisesdiffraction gratings optically connected to a light guide to provide thedirectional light beams having the individual directional light beamintensities and directions. The diffraction gratings are configured toemit or provide the directional light beams by or according todiffractive coupling or scattering out of light guided from within thelight guide, the light being guided as a plurality of guided lightbeams. Further, guided light beams of the guided light beam pluralityare guided within the light guide at different radial directions fromone another. As such, a diffraction grating of the diffraction gratingplurality comprises a grating characteristic that accounts for or thatis a function of a particular radial direction of a guided light beamincident on the diffraction grating. In particular, the gratingcharacteristic may be a function of a relative location of thediffraction grating and a light source configured to provide the guidedlight beam. According to various embodiments, the grating characteristicis configured to account for the radial direction of the guided lightbeam to insure a correspondence between the emitted directional lightbeams provide by the diffraction gratings and associated view pixels invarious views of the static or quasi-static multiview image beingdisplayed.

Herein, a ‘multiview display’ is defined as an electronic display ordisplay system configured to provide different views of a multiviewimage in different view directions. A ‘static multiview display’ is adefined as a multiview display configured to display a predetermined orfixed (i.e., static) multiview image, albeit as a plurality of differentviews. A ‘quasi-static multiview display’ is defined herein as a staticmultiview display that may be switched between different fixed multiviewimages or between a plurality of multiview image states, typically as afunction of time. Switching between the different fixed multiview imagesor multiview image states may provide a rudimentary form of animation,for example. Further, as defined herein, a quasi-static multiviewdisplay is a type of static multiview display. As such, no distinctionis made between a purely static multiview display or image and aquasi-static multiview display or image, unless such distinction isnecessary for proper understanding.

FIG. 1A illustrates a perspective view of a multiview display 10 in anexample, according to an embodiment consistent with the principlesdescribed herein. As illustrated in FIG. 1A, the multiview display 10comprises a diffraction grating on a screen 12 configured to display aview pixel in a view 14 within or of a multiview image 16 (orequivalently a view 14 of the multiview display 10). The screen 12 maybe a display screen of an automobile, a telephone (e.g., mobiletelephone, smart phone, etc.), a tablet computer, a laptop computer, acomputer monitor of a desktop computer, a camera display, or anelectronic display of substantially any other device, for example.

The multiview display 10 provides different views 14 of the multiviewimage 16 in different view directions 18 (i.e., in different principalangular directions) relative to the screen 12. The view directions 18are illustrated as arrows extending from the screen 12 in variousdifferent principal angular directions. The different views 14 areillustrated as shaded polygonal boxes at the termination of the arrows(i.e., depicting the view directions 18). Thus, when the multiviewdisplay 10 (e.g., as illustrated in FIG. 1A) is rotated about they-axis, a viewer sees different views 14. On the other hand (asillustrated) when the multiview display 10 in FIG. 1A is rotated aboutthe x-axis the viewed image is unchanged until no light reaches theviewer's eyes (as illustrated).

Note that, while the different views 14 are illustrated as being abovethe screen 12, the views 14 actually appear on or in a vicinity of thescreen 12 when the multiview image 16 is displayed on the multiviewdisplay 10 and viewed by the viewer. Depicting the views 14 of themultiview image 16 above the screen 12 as in FIG. 1A is done only forsimplicity of illustration and is meant to represent viewing themultiview display 10 from a respective one of the view directions 18corresponding to a particular view 14. Further, in FIG. 1A only threeviews 14 and three view directions 18 are illustrated, all by way ofexample and not limitation.

A view direction or equivalently a light beam having a directioncorresponding to a view direction of a multiview display generally has aprincipal angular direction given by angular components {θ, ϕ}, bydefinition herein. The angular component θ is referred to herein as the‘elevation component’ or ‘elevation angle’ of the light beam. Theangular component ϕ is referred to as the ‘azimuth component’ or‘azimuth angle’ of the light beam. By definition, the elevation angle θis an angle in a vertical plane (e.g., perpendicular to a plane of themultiview display screen while the azimuth angle ϕ is an angle in ahorizontal plane (e.g., parallel to the multiview display screen plane).

FIG. 1B illustrates a graphical representation of the angular components{θ, ϕ} of a light beam 20 having a particular principal angulardirection corresponding to a view direction (e.g., view direction 18 inFIG. 1A) of a multiview display in an example, according to anembodiment consistent with the principles described herein. In addition,the light beam 20 is emitted or emanates from a particular point, bydefinition herein. That is, by definition, the light beam 20 has acentral ray associated with a particular point of origin within themultiview display. FIG. 1B also illustrates the light beam (or viewdirection) point of origin O.

Further herein, the term ‘multiview’ as used in the terms ‘multiviewimage’ and ‘multiview display’ is defined as a plurality of viewsrepresenting different perspectives or including angular disparitybetween views of the view plurality. In addition, herein the term‘multiview’ explicitly includes more than two different views (i.e., aminimum of three views and generally more than three views), bydefinition herein. As such, ‘multiview display’ as employed herein isexplicitly distinguished from a stereoscopic display that includes onlytwo different views to represent a scene or an image. Note however,while multiview images and multiview displays may include more than twoviews, by definition herein, multiview images may be viewed (e.g., on amultiview display) as a stereoscopic pair of images by selecting onlytwo of the multiview views to view at a time (e.g., one view per eye).

In the multiview display, a ‘multiview pixel’ is defined herein as a setor plurality of view pixels representing pixels in each of a similarplurality of different views of a multiview display. Equivalently, amultiview pixel may have an individual view pixel corresponding to orrepresenting a pixel in each of the different views of the multiviewimage to be displayed by the multiview display. Moreover, the viewpixels of the multiview pixel are so-called ‘directional pixels’ in thateach of the view pixels is associated with a predetermined viewdirection of a corresponding one of the different views, by definitionherein. Further, according to various examples and embodiments, thedifferent view pixels represented by the view pixels of a multiviewpixel may have equivalent or at least substantially similar locations orcoordinates in each of the different views. For example, a firstmultiview pixel may have individual view pixels corresponding to viewpixels located at {x₁, y₁} in each of the different views of a multiviewimage, while a second multiview pixel may have individual view pixelscorresponding to view pixels located at {x₂, y₂} in each of thedifferent views, and so on.

In some embodiments, a number of view pixels in a multiview pixel may beequal to a number of views of the multiview display. For example, themultiview pixel may provide eight (8) view pixels associated with amultiview display having 8 different views. Alternatively, the multiviewpixel may provide sixty-four (64) view pixels associated with amultiview display having 64 different views. In another example, themultiview display may provide an eight by four array of views (i.e., 32views) and the multiview pixel may include thirty-two 32 view pixels(i.e., one for each view). Further, according to some embodiments, anumber of multiview pixels of the multiview display may be substantiallyequal to a number of pixels that make up a selected view of themultiview display.

Herein, a ‘light guide’ is defined as a structure that guides lightwithin the structure using total internal reflection. In particular, thelight guide may include a core that is substantially transparent at anoperational wavelength of the light guide. In various examples, the term‘light guide’ generally refers to a dielectric optical waveguide thatemploys total internal reflection to guide light at an interface betweena dielectric material of the light guide and a material or medium thatsurrounds that light guide. By definition, a condition for totalinternal reflection is that a refractive index of the light guide isgreater than a refractive index of a surrounding medium adjacent to asurface of the light guide material. In some embodiments, the lightguide may include a coating in addition to or instead of theaforementioned refractive index difference to further facilitate thetotal internal reflection. The coating may be a reflective coating, forexample. The light guide may be any of several light guides including,but not limited to, one or both of a plate or slab guide and a stripguide.

Further herein, the term ‘plate’ when applied to a light guide as in a‘plate light guide’ is defined as a piece-wise or differentially planarlayer or sheet, which is sometimes referred to as a ‘slab’ guide. Inparticular, a plate light guide is defined as a light guide configuredto guide light in two substantially orthogonal directions bounded by atop surface and a bottom surface (i.e., opposite surfaces) of the lightguide. Further, by definition herein, the top and bottom surfaces areboth separated from one another and may be substantially parallel to oneanother in at least a differential sense. That is, within anydifferentially small section of the plate light guide, the top andbottom surfaces are substantially parallel or co-planar.

In some embodiments, the plate light guide may be substantially flat(i.e., confined to a plane) and therefore, the plate light guide is aplanar light guide. In other embodiments, the plate light guide may becurved in one or two orthogonal dimensions. For example, the plate lightguide may be curved in a single dimension to form a cylindrical shapedplate light guide. However, any curvature has a radius of curvaturesufficiently large to ensure that total internal reflection ismaintained within the plate light guide to guide light.

Herein, a ‘diffraction grating’ is generally defined as a plurality offeatures (i.e., diffractive features) arranged to provide diffraction oflight incident on the diffraction grating. In some examples, theplurality of features may be arranged in a periodic or quasi-periodicmanner having one or more grating spacings between pairs of thefeatures. For example, the diffraction grating may comprise a pluralityof features (e.g., a plurality of grooves or ridges in a materialsurface) arranged in a one-dimensional (1D) array. In other examples,the diffraction grating may be a two-dimensional (2D) array of features.The diffraction grating may be a 2D array of bumps on or holes in amaterial surface, for example. According to various embodiments andexamples, the diffraction grating may be a sub-wavelength grating havinga grating spacing or distance between adjacent diffractive features thatis less than about a wavelength of light that is to be diffracted by thediffraction grating.

As such, and by definition herein, the ‘diffraction grating’ is astructure that provides diffraction of light incident on the diffractiongrating. If the light is incident on the diffraction grating from alight guide, the provided diffraction or diffractive scattering mayresult in, and thus be referred to as, ‘diffractive coupling’ in thatthe diffraction grating may couple light out of the light guide bydiffraction. The diffraction grating also redirects or changes an angleof the light by diffraction (i.e., at a diffractive angle). Inparticular, as a result of diffraction, light leaving the diffractiongrating generally has a different propagation direction than apropagation direction of the light incident on the diffraction grating(i.e., incident light). The change in the propagation direction of thelight by diffraction is referred to as ‘diffractive redirection’ herein.Hence, the diffraction grating may be understood to be a structurecomprising diffractive features that diffractively redirects lightincident on the diffraction grating and, if the light is incident from alight guide, the diffraction grating may also diffractively couple outthe light from the light guide.

Further, by definition herein, the features of a diffraction grating arereferred to as ‘diffractive features’ and may be one or more of at, inand on a material surface (i.e., a boundary between two materials). Thesurface may be a surface of a light guide, for example. The diffractivefeatures may include any of a variety of structures that diffract lightincluding, but not limited to, one or more of grooves, ridges, holes andbumps at, in or on the surface. For example, the diffraction grating mayinclude a plurality of substantially parallel grooves in the materialsurface. In another example, the diffraction grating may include aplurality of parallel ridges rising out of the material surface. Thediffractive features (e.g., grooves, ridges, holes, bumps, etc.) mayhave any of a variety of cross-sectional shapes or profiles that providediffraction including, but not limited to, one or more of a sinusoidalprofile, a rectangular profile (e.g., a binary diffraction grating), atriangular profile and a saw tooth profile (e.g., a blazed grating).

As described further below, a diffraction grating herein may have agrating characteristic, including one or more of a feature spacing orpitch, an orientation and a size (such as a width or length of thediffraction grating). Further, the grating characteristic may selectedor chosen to be a function of the angle of incidence of light beams onthe diffraction grating, a distance of the diffraction grating from alight source or both. In particular, the grating characteristic of adiffraction grating may be chosen to depend on a relative location ofthe light source and a location of the diffraction grating, according tosome embodiments. By appropriately varying the grating characteristic ofthe diffraction grating, both an intensity and a principal angulardirection of a light beam diffracted (e.g., diffractively coupled-out ofa light guide) by the diffraction grating (i.e., a ‘directional lightbeam’) corresponds to an intensity and a view direction of a view pixelof the multiview image.

According to various examples described herein, a diffraction grating(e.g., a diffraction grating of a multiview pixel, as described below)may be employed to diffractively scatter or couple light out of a lightguide (e.g., a plate light guide) as a light beam. In particular, adiffraction angle θ_(m) of or provided by a locally periodic diffractiongrating may be given by equation (1) as:

$\begin{matrix}{\theta_{m} = {\sin^{- 1}\left( {{n\; \sin \; \theta_{i}} - \frac{m\; \lambda}{d}} \right)}} & (1)\end{matrix}$

where λ is a wavelength of the light, m is a diffraction order, n is anindex of refraction of a light guide, d is a distance or spacing betweenfeatures of the diffraction grating, θ_(i) is an angle of incidence oflight on the diffraction grating. For simplicity, equation (1) assumesthat the diffraction grating is adjacent to a surface of the light guideand a refractive index of a material outside of the light guide is equalto one (i.e., n_(out)=1). In general, the diffraction order m is givenby an integer. A diffraction angle θ_(m) of a light beam produced by thediffraction grating may be given by equation (1) where the diffractionorder is positive (e.g., m>0). For example, first-order diffraction isprovided when the diffraction order m is equal to one (i.e., m=1).

FIG. 2 illustrates a cross-sectional view of a diffraction grating 30 inan example, according to an embodiment consistent with the principlesdescribed herein. For example, the diffraction grating 30 may be locatedon a surface of a light guide 40. In addition, FIG. 2 illustrates alight beam (or a collection of light beams) 50 incident on thediffraction grating 30 at an incident angle θ_(i). The light beam 50 isa guided light beam within the light guide 40. Also illustrated in FIG.2 is a coupled-out light beam (or a collection of light beams) 60diffractively produced and coupled-out by the diffraction grating 30 asa result of diffraction of the incident light beam 50. The coupled-outlight beam 60 has a diffraction angle θ_(m) (or ‘principal angulardirection’ herein) as given by equation (1). The coupled-out light beam60 may correspond to a diffraction order ‘m’ of the diffraction grating30, for example.

According to various embodiments, the principal angular direction of thevarious light beams is determined by the grating characteristicincluding, but not limited to, one or more of a size (e.g., a length, awidth, an area, etc.) of the diffraction grating, an orientation, and afeature spacing. Further, a light beam produced by the diffractiongrating has a principal angular direction given by angular components{θ, ϕ}, by definition herein, and as described above with respect toFIG. 1B.

Herein, a ‘collimated light’ or ‘collimated light beam’ is generallydefined as a beam of light in which rays of the light beam aresubstantially parallel to one another within the light beam (e.g., theguided light beam in the light guide). Further, rays of light thatdiverge or are scattered from the collimated light beam are notconsidered to be part of the collimated light beam, by definitionherein. Moreover, herein a ‘collimator’ is defined as substantially anyoptical device or apparatus that is configured to collimate light.

Herein, a ‘collimation factor’ is defined as a degree to which light iscollimated. In particular, a collimation factor defines an angularspread of light rays within a collimated beam of light, by definitionherein. For example, a collimation factor σ may specify that a majorityof light rays in a beam of collimated light is within a particularangular spread (e.g., +/−σ degrees about a central or principal angulardirection of the collimated light beam). The light rays of thecollimated light beam may have a Gaussian distribution in terms of angleand the angular spread be an angle determined by at one-half of a peakintensity of the collimated light beam, according to some examples.

Herein, a ‘light source’ is defined as a source of light (e.g., anoptical emitter configured to produce and emit light). For example, thelight source may comprise an optical emitter such as a light emittingdiode (LED) that emits light when activated or turned on. In particular,herein the light source may be substantially any source of light orcomprise substantially any optical emitter including, but not limitedto, one or more of a light emitting diode (LED), a laser, an organiclight emitting diode (OLED), a polymer light emitting diode, aplasma-based optical emitter, a fluorescent lamp, an incandescent lamp,and virtually any other source of light. The light produced by the lightsource may have a color (i.e., may include a particular wavelength oflight), or may be a range of wavelengths (e.g., white light). In someembodiments, the light source may comprise a plurality of opticalemitters. For example, the light source may include a set or group ofoptical emitters in which at least one of the optical emitters produceslight having a color, or equivalently a wavelength, that differs from acolor or wavelength of light produced by at least one other opticalemitter of the set or group. The different colors may include primarycolors (e.g., red, green, blue) for example.

Further, as used herein, the article ‘a’ is intended to have itsordinary meaning in the patent arts, namely ‘one or more’. For example,‘a diffraction grating’ means one or more diffraction gratings and assuch, ‘the diffraction grating’ means ‘the diffraction grating(s)’herein. Also, any reference herein to ‘top’, ‘bottom’, ‘upper’, ‘lower’,‘up’, ‘down’, ‘front’, back’, ‘first’, ‘second’, ‘left’ or ‘right’ isnot intended to be a limitation herein. Herein, the term ‘about’ whenapplied to a value generally means within the tolerance range of theequipment used to produce the value, or may mean plus or minus 10%, orplus or minus 5%, or plus or minus 1%, unless otherwise expresslyspecified. Further, the term ‘substantially’ as used herein means amajority, or almost all, or all, or an amount within a range of about51% to about 100%. Moreover, examples herein are intended to beillustrative only and are presented for discussion purposes and not byway of limitation.

According to some embodiments of the principles described herein, amultiview display configured to provide multiview images and moreparticularly static multiview images (i.e., a static multiview display)is provided. FIG. 3A illustrates a plan view of a static multiviewdisplay 100 in an example, according to an embodiment consistent withthe principles described herein. FIG. 3B illustrates a cross-sectionalview of a portion of a static multiview display 100 in an example,according to an embodiment consistent with the principles describedherein. In particular, FIG. 3B may illustrate a cross section through aportion of the static multiview display 100 of FIG. 3A, the crosssection being in an x-z plane. FIG. 3C illustrates a perspective view ofa static multiview display 100 in an example, according to an embodimentconsistent with the principles described herein. According to someembodiments, the illustrated static multiview display 100 is configuredto provide purely a static multiview image, while in others the staticmultiview display 100 may be configured to provide a plurality ofmultiview images and therefore functions as (or is) a quasi-staticmultiview display 100. For example, the static multiview display 100 maybe switchable between different fixed multiview images or equivalentlybetween a plurality of multiview image states, as described below.

The static multiview display 100 illustrated in FIGS. 3A-3C isconfigured to provide a plurality of directional light beams 102, eachdirectional light beam 102 of the plurality having an intensity and aprincipal angular direction. Together, the plurality of directionallight beams 102 represents various view pixels of a set of views of amultiview image that the static multiview display 100 is configured toprovide or display. In some embodiments, the view pixels may beorganized into multiview pixels to represent the various different viewsof the multiview images.

As illustrated, the static multiview display 100 comprises a light guide110. The light guide may be a plate light guide (as illustrated), forexample. The light guide 110 is configured to guide light along a lengthof the light guide 110 as guided light or more particularly as guidedlight beams 112. For example, the light guide 110 may include adielectric material configured as an optical waveguide. The dielectricmaterial may have a first refractive index that is greater than a secondrefractive index of a medium surrounding the dielectric opticalwaveguide. The difference in refractive indices is configured tofacilitate total internal reflection of the guided light beams 112according to one or more guided modes of the light guide 110, forexample.

In some embodiments, the light guide 110 may be a slab or plate opticalwaveguide comprising an extended, substantially planar sheet ofoptically transparent, dielectric material. The substantially planarsheet of dielectric material is configured to guide the guided lightbeams 112 using total internal reflection. According to variousexamples, the optically transparent material of the light guide 110 mayinclude or be made up of any of a variety of dielectric materialsincluding, but not limited to, one or more of various types of glass(e.g., silica glass, alkali-aluminosilicate glass, borosilicate glass,etc.) and substantially optically transparent plastics or polymers(e.g., poly(methyl methacrylate) or ‘acrylic glass’, polycarbonate,etc.). In some examples, the light guide 110 may further include acladding layer (not illustrated) on at least a portion of a surface(e.g., one or both of the top surface and the bottom surface) of thelight guide 110. The cladding layer may be used to further facilitatetotal internal reflection, according to some examples.

According to various embodiments, the light guide 110 is configured toguide the guided light beams 112 according to total internal reflectionat a non-zero propagation angle between a first surface 110′ (e.g., a‘front’ surface) and a second surface 110″ (e.g., a ‘back’ or ‘bottom’surface) of the light guide 110. In particular, the guided light beams112 propagate by reflecting or ‘bouncing’ between the first surface 110′and the second surface 110″ of the light guide 110 at the non-zeropropagation angle. Note, the non-zero propagation angle is notexplicitly depicted in FIG. 3B for simplicity of illustration. However,FIG. 3B does illustrate an arrow pointing into a plane of theillustration depicting a general propagation direction 103 of the guidedlight beams 112 along the light guide length.

As defined herein, a ‘non-zero propagation angle’ is an angle relativeto a surface (e.g., the first surface 110′ or the second surface 110″)of the light guide 110. Further, the non-zero propagation angle is bothgreater than zero and less than a critical angle of total internalreflection within the light guide 110, according to various embodiments.For example, the non-zero propagation angle of the guided light beam 112may be between about ten (10) degrees and about fifty (50) degrees or,in some examples, between about twenty (20) degrees and about forty (40)degrees, or between about twenty-five (25) degrees and about thirty-five(35) degrees. For example, the non-zero propagation angle may be aboutthirty (30) degrees. In other examples, the non-zero propagation anglemay be about 20 degrees, or about 25 degrees, or about 35 degrees.Moreover, a specific non-zero propagation angle may be chosen (e.g.,arbitrarily) for a particular implementation as long as the specificnon-zero propagation angle is chosen to be less than the critical angleof total internal reflection within the light guide 110.

As illustrated in FIGS. 3A and 3C, the static multiview display 100further comprise a light source 120. The light source 120 is located atan input location 116 on the light guide 110. For example, the lightsource 120 may be located adjacent to an edge or side 114 of the lightguide 110, as illustrated. The light source 120 is configured to providelight within the light guide 110 as the plurality of guided light beams112. Further, the light source 120 provides the light such thatindividual guided light beams 112 of the guided light beam pluralityhave different radial directions 118 from one another.

In particular, light emitted by the light source 120 is configured enterthe light guide 110 and to propagate as the plurality of guided lightbeams 112 in a radial pattern away from the input location 116 andacross or along a length of the light guide 110. Further, the individualguided light beams 112 of the guided light beam plurality have differentradial directions from one another by virtue of the radial pattern ofpropagation away from the input location 116. For example, the lightsource 120 may be butt-coupled to the side 114. The light source 120being butt-coupled may facilitate introduction of light in a fan-shapepattern to provide the different radial directions of the individualguided light beams 112, for example. According to some embodiments, thelight source 120 may be or at least approximate a ‘point’ source oflight at the input location 116 such that the guided light beams 112propagate along the different radial directions 118 (i.e., as theplurality of guided light beams 112).

In some embodiments, the input location 116 of the light source 120 ison a side 114 of the light guide 110 near or about at a center or amiddle of the side 114. In particular, in FIGS. 3A and 3C, the lightsource 120 is illustrated at an input location 116 that is approximatelycentered on (e.g., at a middle of) the side 114 (i.e., the ‘input side’)of the light guide 110. Alternatively (not illustrated), the inputlocation 116 may be away from the middle of the side 114 of the lightguide 110. For example, the input location 116 may be at a corner of thelight guide 110. For example, the light guide 110 may have a rectangularshape (e.g., as illustrated) and the input location 116 of the lightsource 120 may be at a corner of the rectangular-shaped light guide 110(e.g., a corner of the input side 114).

In various embodiments, the light source 120 may comprise substantiallyany source of light (e.g., optical emitter) including, but not limitedto, one or more light emitting diodes (LEDs) or a laser (e.g., laserdiode). In some embodiments, the light source 120 may comprise anoptical emitter configured produce a substantially monochromatic lighthaving a narrowband spectrum denoted by a particular color. Inparticular, the color of the monochromatic light may be a primary colorof a particular color space or color model (e.g., an RGB color model).In other examples, the light source 120 may be a substantially broadbandlight source configured to provide substantially broadband orpolychromatic light. For example, the light source 120 may provide whitelight. In some embodiments, the light source 120 may comprise aplurality of different optical emitters configured to provide differentcolors of light. The different optical emitters may be configured toprovide light having different, color-specific, non-zero propagationangles of the guided light corresponding to each of the different colorsof light.

In some embodiments, the guided light beams 112 produced by couplinglight from the light source 120 into the light guide 110 may beuncollimated or at least substantially uncollimated. In otherembodiments, the guided light beams 112 may be collimated (i.e., theguided light beams 112 may be collimated light beams). As such, in someembodiments, the static multiview display 100 may include a collimator(not illustrated) between the light source 120 and the light guide 110.Alternatively, the light source 120 may further comprise a collimator.The collimator is configured to provide guided light beams 112 withinthe light guide 110 that are collimated. In particular, the collimatoris configured to receive substantially uncollimated light from one ormore of the optical emitters of the light source 120 and to convert thesubstantially uncollimated light into collimated light. In someexamples, the collimator may be configured to provide collimation in aplane (e.g., a ‘vertical’ plane) that is substantially perpendicular tothe propagation direction of the guided light beams 112. That is, thecollimation may provide collimated guided light beams 112 having arelatively narrow angular spread in a plane perpendicular to a surfaceof the light guide 110 (e.g., the first or second surface 110′, 110″),for example. According to various embodiments, the collimator maycomprise any of a variety of collimators including, but not limited to alens, a reflector or mirror (e.g., tilted collimating reflector), or adiffraction grating (e.g., a diffraction grating-based barrelcollimator) configured to collimate the light, e.g., from the lightsource 120.

Further, in some embodiments, the collimator may provide collimatedlight one or both of having the non-zero propagation angle and beingcollimated according to a predetermined collimation factor. Moreover,when optical emitters of different colors are employed, the collimatormay be configured to provide the collimated light having one or both ofdifferent, color-specific, non-zero propagation angles and havingdifferent color-specific collimation factors. The collimator is furtherconfigured to communicate the collimated light to the light guide 110 topropagate as the guided light beams 112, in some embodiments.

Use of collimated or uncollimated light may impact the multiview imagethat may be provided by the static multiview display 100, in someembodiments. For example, if the guided light beams 112 are collimatedwithin the light guide 110, the emitted directional light beams 102 mayhave a relatively narrow or confined angular spread in at least twoorthogonal directions. Thus, the static multiview display 100 mayprovide a multiview image having a plurality of different views in anarray having two different directions (e.g., an x-direction and ay-direction). However, if the guided light beams 112 are substantiallyuncollimated, the multiview image may provide view parallax, but may notprovide a full, two-dimensional array of different views. In particular,if the guided light beams 112 are uncollimated (e.g., along the z-axis),the multiview image may provide different multiview images exhibiting‘parallax 3D’ when rotated about the y-axis (e.g., as illustrated inFIG. 1A). On the other hand, if the static multiview display 100 isrotated around the x-axis, for example, the multiview image and viewsthereof may remain substantially unchanged or the same because thedirectional light beams 102 of the directional light beam plurality havea broad angular range within the y-z plane. Thus, the multiview imageprovided may be ‘parallax only’ providing an array of views in only onedirection and not two.

The static multiview display 100 illustrated in FIGS. 3A-3C furthercomprises a plurality of diffraction gratings 130 configured to emitdirectional light beams 102 of the directional light beam plurality. Asmentioned above and according to various embodiments, the directionallight beams 102 emitted by the plurality of diffraction gratings 130 mayrepresent a multiview image. In particular, the directional light beams102 emitted by the plurality of diffraction gratings 130 may beconfigured to create the multiview image to display information, e.g.,information having 3D content. Further, the diffraction gratings 130 mayemit the directional light beams 102 when the light guide 110 isilluminated from the side 114 by the light source 120, as is furtherdescribed below.

According to various embodiments, a diffraction grating 130 of thediffraction grating plurality are configured to provide from a portionof a guided light beam 112 of the guided light beam plurality adirectional light beam 102 of the directional light beam plurality.Further, the diffraction grating 130 is configured to provide thedirectional light beam 102 having both an intensity and a principalangular direction corresponding to an intensity and a view direction ofa view pixel of the multiview image. In some embodiments, thediffraction gratings 130 of the diffraction grating plurality generallydo not intersect, overlap or otherwise touch one another, according tosome embodiments. That is, each diffraction grating 130 of thediffraction grating plurality is generally distinct and separated fromother ones of the diffraction gratings 130, according to variousembodiments.

As illustrated in FIG. 3B, the directional light beams 102 may, at leastin part, propagate in a direction that differs from and in someembodiments is orthogonal to an average or general propagation direction103 of a guided light beams 112 within the light guide 110. For example,as illustrated in FIG. 3B, the directional light beam 102 from adiffraction grating 130 may be substantially confined to the x-z plane,according to some embodiments.

According to various embodiments, each of the diffraction gratings 130of the diffraction grating plurality has an associated gratingcharacteristic. The associated grating characteristic of eachdiffraction grating depends on, is defined by, or is a function of aradial direction 118 of the guided light beam 112 incident on thediffraction grating from the light source 120. Further, in someembodiment, the associated grating characteristic is further determinedor defined by a distance between the diffraction grating 130 and theinput location 116 of the light source 120. For example, the associatedcharacteristic may be a function of the distance D between diffractiongrating 130 a and input location 116 and the radial direction 118 a ofthe guided light beam 112 incident on the diffraction grating 130 a, asillustrated in FIG. 3A. Stated differently, an associated gratingcharacteristic of a diffraction grating 130 in the plurality of thediffraction gratings 130 depends on the input location 116 of the lightsource and a particular location of the diffraction grating 130 on asurface of the light guide 110 relative to the input location 116.

FIG. 3A illustrates two different diffraction gratings 130 a and 130 bhaving different spatial coordinates (x₁, y₁) and (x₂, y₂), whichfurther have different grating characteristics to compensate or accountfor the different radial directions 118 a and 118 b of the plurality ofguided light beams 112 from the light source 120 that are incident onthe diffraction gratings 130. Similarly, the different gratingcharacteristics of the two different diffraction gratings 130 a and 130b account for different distances of the respective diffraction gratings130 a, 130 b from the light source input location 116 determined by thedifferent spatial coordinates (x₁, y₁) and (x₂, y₂).

FIG. 3C illustrates an example of a plurality of directional light beams102 that may be provided by the static multiview display 100. Inparticular, as illustrated, different sets of diffraction gratings 130of the diffraction grating plurality are illustrated emittingdirectional light beams 102 having different principal angulardirections from one another. The different principal angular directionsmay correspond to different view directions of the static multiviewdisplay 100, according to various embodiments. For example, a first setof the diffraction gratings 130 may diffractively couple out portions ofincident guided light beams 112 (illustrated as dashed lines) to providea first set of directional light beams 102′ having a first principalangular direction corresponding to a first view direction (or a firstview) of the static multiview display 100. Similarly, a second set ofdirectional light beams 102″ and a third set of directional light beams102′″ having principal angular directions corresponding to a second viewdirection (or a second view) and a third view direction (or third view),respectively of the static multiview display 100 may be provided bydiffractive coupling out of portions of incident guided light beams 112by respective second third sets of diffraction gratings 130, and so on,as illustrated. Also illustrated in FIG. 3C are a first view 14′, asecond view 14″, and a third view 14′″, of a multiview image 16 that maybe provided by the multiview display 100. The illustrated first, second,and third views 14′, 14″, 14′″, represent different perspective views ofan object and collectively are the displayed multiview image 16 (e.g.,equivalent to the multiview image 16 illustrated in FIG. 1A).

In general, the grating characteristic of a diffraction grating 130 mayinclude one or more of a diffractive feature spacing or pitch, a gratingorientation and a grating size (or extent) of the diffraction grating.Further, in some embodiments, a diffraction-grating coupling efficiency(such as the diffraction-grating area, the groove depth or ridge height,etc.) may be a function of the distance from the input location 116 tothe diffraction grating. For example, the diffraction grating couplingefficiency may be configured to increase as a function of distance, inpart, to correct or compensate for a general decrease in the intensityof the guided light beams 112 associated with the radial spreading andother loss factors. Thus, an intensity of the directional light beam 102provided by the diffraction grating 130 and corresponding to anintensity of a corresponding view pixel may be determined, in part, by adiffractive coupling efficiency of the diffraction grating 130,according to some embodiments.

FIG. 4 illustrates a plan view of a static multiview display 100 in anexample, according to an embodiment consistent with the principlesdescribed herein. In FIG. 4, illumination volumes 134 in an angularspace that is a distance D from input location 116 of the light source120 at the side 114 of the light guide 110 are shown. Note that theillumination volume has a wider angular size as the radial direction ofpropagation of the plurality of guided light beams 112 changes in angleaway from the y-axis and towards the x-axis. For example, illuminationvolume 134 b is wider than illumination volume 134 a, as illustrated.

Referring again to FIG. 3B, the plurality of diffraction gratings 130may be located at or adjacent to the first surface 110′ of the lightguide 110, which is the light beam emission surface of the light guide110, as illustrated. For example, the diffraction gratings 130 may betransmission mode diffraction gratings configured to diffractivelycouple out the guided light portion through the first surface 110′ asthe directional light beams 102. Alternatively, the plurality ofdiffraction gratings 130 may be located at or adjacent to the secondsurface 110″ opposite from a light beam emission surface of the lightguide 110 (i.e., the first surface 110′). In particular, the diffractiongratings 130 may be reflection mode diffraction gratings. As reflectionmode diffraction gratings, the diffraction gratings 130 are configuredto both diffract the guided light portion and to reflect the diffractedguided light portion toward the first surface 110′ to exit through thefirst surface 110′ as the diffractively scattered or coupled-outdirectional light beams 102. In other embodiments (not illustrated), thediffraction gratings 130 may be located between the surfaces of thelight guide 110, e.g., as one or both of a transmission mode diffractiongrating and a reflection mode diffraction grating.

In some embodiments described herein, the principal angular directionsof the directional light beams 102 may include an effect of refractiondue to the directional light beams 102 exiting the light guide 110 at alight guide surface. For example, when the diffraction gratings 130 arelocated at or adjacent to second surface 110″, the directional lightbeams 102 may be refracted (i.e., bent) because of a change inrefractive index as the directional light beams 102 cross the firstsurface 110′, by way of example and not limitation.

In some embodiments, provision may be made to mitigate, and in someinstances even substantially eliminate, various sources of spuriousreflection of the guided light beams 112 within the static multiviewdisplay 100, especially when those spurious reflection sources mayresult in emission of unintended direction light beams and, in turn, theproduction of unintended images by static multiview display 100.Examples of various potential spurious reflection sources include, butnot limited to, sidewalls of the light guide 110 that may produce asecondary reflection of the guided light beams 112. Reflection fromvarious spurious reflection sources within the static multiview display100 may be mitigated by any of a number of methods including, but notlimited to absorption and controlled redirection of the spuriousreflection.

FIG. 5A illustrates a plan view of a static multiview display 100including spurious reflection mitigation in an example, according to anembodiment consistent with the principles described herein. FIG. 5Billustrates a plan view of a static multiview display 100 includingspurious reflection mitigation in an example, according to anotherembodiment consistent with the principles described herein. Inparticular, FIGS. 5A and 5B illustrate the static multiview display 100comprising the light guide 110, the light source 120, and the pluralityof diffraction gratings 130. Also illustrated is the plurality of guidedlight beams 112 with at least one guided light beam 112 of the pluralitybeing incident on a sidewall 114 a, 114 b of the light guide 110. Apotential spurious reflection of the guided light beam 112 by thesidewalls 114 a, 114 b is illustrated by a dashed arrow representing areflected guided light beam 112′.

In FIG. 5A, the static multiview display 100 further comprises anabsorbing layer 119 at the sidewalls 114 a, 114 b of the light guide110. The absorbing layer 119 is configured to absorb incident light fromthe guided light beams 112. The absorbing layer may comprisesubstantially any optical absorber including, but not limited to, blackpaint applied to the sidewalls 114 a, 114 b for example. As illustratedin 5A, the absorbing layer 119 is applied to the sidewall 114 b, whilethe sidewall 114 a lacks the absorbing layer 119, by way of example andnot limitation. The absorbing layer 119 intercepts and absorbs theincident guided light beam 112 effectively preventing or mitigating theproduction of the potential spurious reflection from sidewall 114 b. Onthe other hand, guided light beam 112 incident on the sidewall 114 areflects resulting in the production of the reflected guided light beam112′, illustrated by way of example and not limitation.

FIG. 5B illustrates spurious reflection mitigation using controlledreflection angle. In particular, the light guide 110 of the staticmultiview display 100 illustrated in FIG. 5B comprises slanted sidewalls114 a, 114 b. The slanted sidewalls have a slant angle configured topreferentially direct the reflected guided light beam 112′ substantiallyaway from the diffraction gratings 130. As such, the reflected guidedlight beam 112′ is not diffractively coupled out of the light guide 110as an unintended directional light beam. The slant angle of thesidewalls 114 a, 114 b may be in the x-y plane, as illustrated. In otherexamples (not illustrated), the slant angle of the sidewalls 114 a, 114b may be in another plane, e.g., the x-z plane to direct the reflectedguided light beam 112′ out a top or bottom surface of the light guide110. Note that FIG. 5B illustrates sidewalls 114 a, 114 b that include aslant along only a portion of thereof, by way of example and notlimitation.

According to some embodiment, the static multiview display 100 maycomprise a plurality of light sources 120 that are laterally offset fromone another. The lateral offset of light sources 120 of the light sourceplurality may provide a difference in the radial directions of variousguided light beams 102 at or between individual diffraction gratings130. The difference, in turn, may facilitate providing animation of adisplayed multiview image, according to some embodiments. Thus, thestatic multiview display 100 may be a quasi-static multiview display100, in some embodiments.

FIG. 6A illustrates a plan view of a static multiview display 100 in anexample, according to an embodiment consistent with the principlesdescribed herein. FIG. 6B illustrates a plan view of the staticmultiview display 100 of FIG. 6A in another example, according to anembodiment consistent with the principles described herein. The staticmultiview display 100 illustrated in FIGS. 6A and 6B comprises a lightguide 110 with a plurality of diffraction gratings 130. In addition, thestatic multiview display 100 further comprises a plurality of lightsources 120 that are laterally offset from each other and configured toseparately provide guided light beams 112 having different radialdirections 118 from one another, as illustrated.

In particular, FIGS. 6A and 6B illustrate a first light source 120 a ata first input location 116 a and a second light source 120 b at a secondinput location 116 b on the side 114 of the light guide 110. The firstand second input locations 116 a, 116 b are laterally offset or shiftedfrom one another along the side 114 (i.e., in an x-direction) to providethe lateral offset of respective first and second light sources 120 a,120 b. Additionally, each of the first and second light sources 120 a,120 b of the plurality of light sources 120 provide a differentplurality of guided light beams 112 having respective different radialdirections from one another. For example, the first light source 120 amay provide a first plurality of guided light beams 112 a having a firstset of different radial directions 118 a and the second light source 120b may provide a second plurality of guided light beams 112 b having asecond set of different radial directions 118 b, as illustrated in FIGS.6A and 6B, respectively. Further, the first and second pluralities ofguided light beams 112 a, 112 b generally have sets of different radialdirections 118 a, 118 b that also differ from one another as sets byvirtue of the lateral offset of the first and second light sources 120a, 120 b, as illustrated.

Thus, the plurality of diffraction gratings 130 emit directional lightbeams representing different multiview images that are shifted in a viewspace from one another (e.g., angularly shifted in view space). Thus, byswitching between the first and second light sources 120 a, 120 b, thestatic multiview display 100 may provide ‘animation’ of the multiviewimages, such as a time-sequenced animation. In particular, bysequentially illuminating the first and second light sources 120 a, 120b during different sequential time intervals or periods, staticmultiview display 100 may be configured to shift an apparent location ofthe multiview image during the different time periods, for example. Thisshift in apparent location provided by the animation may represent andexample of operating the static multiview display 100 as a quasi-staticmultiview display 100 to provide a plurality of multiview image states,according to some embodiments.

According to various embodiments, as described above with respect toFIGS. 3A-3C, the directional light beams 102 of the static multiviewdisplay 100 are emitted using diffraction (e.g., by diffractivescattering or diffractive coupling). In some embodiments, the pluralityof the diffraction gratings 130 may be organized as multiview pixels,each multiview pixel including a set of diffraction gratings 130comprising one or more diffraction gratings 130 from the diffractiongrating plurality. Further, as has been discussed above, the diffractiongrating(s) 130 have diffraction characteristics that are a function ofradial location on the light guide 110 as well as being a function of anintensity and direction of the directional light beams 102 emitted bythe diffraction grating(s) 130.

FIG. 7A illustrates a plan view of a diffraction grating 130 of amultiview display in an example, according to an embodiment consistentwith the principles described herein. FIG. 7B illustrates a plan view ofa set of diffraction gratings 130 organized as a multiview pixel 140 inan example, according to another embodiment consistent with theprinciples described herein. As illustrated in FIGS. 7A and 7B, each ofthe diffraction gratings 130 comprises a plurality of diffractivefeatures spaced apart from one another according to a diffractivefeature spacing (which is sometimes referred to as a ‘grating spacing’)or grating pitch. The diffractive feature spacing or grating pitch isconfigured to provide diffractive coupling out or scattering of theguided light portion from within the light guide. In FIGS. 7A-7B, thediffraction gratings 130 are on a surface of a light guide 110 of themultiview display (e.g., the static multiview display 100 illustrated inFIGS. 3A-3C).

According to various embodiments, the spacing or grating pitch of thediffractive features in the diffraction grating 130 may besub-wavelength (i.e., less than a wavelength of the guided light beams112). Note that, while FIGS. 7A and 7B illustrate the diffractiongratings 130 having a single or uniform grating spacing (i.e., aconstant grating pitch), for simplicity of illustration. In variousembodiments, as described below, the diffraction grating 130 may includea plurality of different grating spacings (e.g., two or more gratingspacings) or a variable diffractive feature spacing or grating pitch toprovide the directional light beams 102, e.g., as is variouslyillustrated in FIGS. 3A-6B. Consequently, FIGS. 7A and 7B are notintended to imply that a single grating pitch is an exclusive embodimentof diffraction grating 130.

According to some embodiments, the diffractive features of thediffraction grating 130 may comprise one or both of grooves and ridgesthat are spaced apart from one another. The grooves or the ridges maycomprise a material of the light guide 110, e.g., the groove or ridgesmay be formed in a surface of the light guide 110. In another example,the grooves or the ridges may be formed from a material other than thelight guide material, e.g., a film or a layer of another material on asurface of the light guide 110.

As discussed previously and shown in FIG. 7A, the configuration of thediffraction features comprises a grating characteristic of thediffraction grating 130. For example, a grating depth of the diffractiongrating may be configured to determine the intensity of the directionallight beams 102 provided by the diffraction grating 130. Alternativelyor additionally, discussed previously and shown in FIGS. 7A-7B, thegrating characteristic comprises one or both of a grating pitch of thediffraction grating 130 and a grating orientation (e.g., the gratingorientation y illustrated in FIG. 7A). In conjunction with the angle ofincidence of the guided light beams, these grating characteristicsdetermine the principal angular direction of the directional light beams102 provided by the diffraction grating 130.

In some embodiments (not illustrated), the diffraction grating 130configured to provide the directional light beams comprises a variableor chirped diffraction grating as a grating characteristic. Bydefinition, the ‘chirped’ diffraction grating is a diffraction gratingexhibiting or having a diffraction spacing of the diffractive features(i.e., the grating pitch) that varies across an extent or length of thechirped diffraction grating. In some embodiments, the chirpeddiffraction grating may have or exhibit a chirp of the diffractivefeature spacing that varies linearly with distance. As such, the chirpeddiffraction grating is a ‘linearly chirped’ diffraction grating, bydefinition. In other embodiments, the chirped diffraction grating of themultiview pixel may exhibit a non-linear chirp of the diffractivefeature spacing. Various non-linear chirps may be used including, butnot limited to, an exponential chirp, a logarithmic chirp or a chirpthat varies in another, substantially non-uniform or random but stillmonotonic manner. Non-monotonic chirps such as, but not limited to, asinusoidal chirp or a triangle or sawtooth chirp, may also be employed.Combinations of any of these types of chirps may also be employed.

In other embodiments, diffraction grating 130 configured to provide thedirectional light beams 102 is or comprises a plurality of diffractiongratings (e.g., sub-gratings). For example, the plurality of diffractiongratings of the diffraction grating 130 may comprise a first diffractiongrating configured to provide a red portion of the directional lightbeams 102. Further, the plurality of diffraction gratings of thediffraction grating 130 may comprise a second diffraction gratingconfigured to provide a green portion of the directional light beams102. Further still, the plurality of diffraction gratings of thediffraction grating 130 may comprise a third diffraction gratingconfigured to provide a blue portion of the directional light beams 102.In some embodiments, individual diffraction gratings of the plurality ofdiffraction gratings may be superimposed on one another. In otherembodiments, the diffraction gratings may be separate diffractiongratings arranged next to one another, e.g., as an array.

More generally, the static multiview display 100 may comprise one ormore instances of multiview pixels 140, which each comprise sets ofdiffraction gratings 130 from the plurality of diffraction gratings 130.As shown in FIG. 7B, the diffraction gratings 130 of the set that makesup a multiview pixel 140 may have different grating characteristics. Thediffraction gratings 130 of the multiview pixel may have differentgrating orientations, for example. In particular, the diffractiongratings 130 of the multiview pixel 140 may have different gratingcharacteristics determined or dictated by a corresponding set of viewsof a multiview image. For example, the multiview pixel 140 may include aset of eight (8) diffraction gratings 130 that, in turn, correspond to 8different views of the static multiview display 100. Moreover, thestatic multiview display 100 may include multiple multiview pixels 140.For example, there may be a plurality of multiview pixels 140 with setsof diffraction gratings 130, each multiview pixels 140 corresponding toa different one of 2048×1024 pixels in each of the 8 different views.

In some embodiments, static multiview display 100 may be transparent orsubstantially transparent. In particular, the light guide 110 and thespaced apart plurality of diffraction gratings 130 may allow light topass through the light guide 110 in a direction that is orthogonal toboth the first surface 110′ and the second surface 110″, in someembodiments. Thus, the light guide 110 and more generally the staticmultiview display 100 may be transparent to light propagating in thedirection orthogonal to the general propagation direction 103 of theguided light beams 112 of the guided light beam plurality. Further, thetransparency may be facilitated, at least in part, by the substantiallytransparency of the diffraction gratings 130.

In accordance with some embodiments of the principles described herein,a multiview display is provided. The multiview display is configured toemit a plurality of directional light beams provided by the multiviewdisplay. Further, the emitted directional light beams may bepreferentially directed toward a plurality of views zones of themultiview display based on the grating characteristics of a plurality ofdiffraction grating that are included in one or more multiview pixels inthe multiview display. Moreover, the diffraction gratings may producedifferent principal angular directions in the directional light beams,which corresponding to different viewing directions for different viewsin a set of views of the multiview image of the multiview display. Insome examples, the multiview display is configured to provide or‘display’ a 3D or multiview image. Different ones of the directionallight beams may correspond to individual view pixels of different‘views’ associated with the multiview image, according to variousexamples. The different views may provide a ‘glasses free’ (e.g.,autostereoscopic) representation of information in the multiview imagebeing displayed by the multiview display, for example.

FIG. 8 illustrates a block diagram of a static multiview display 200 inan example, according to an embodiment consistent with the principlesdescribed herein. According to various embodiments, the static multiviewdisplay 200 is configured to display a multiview image according todifferent views in different view directions. In particular, a pluralityof directional light beams 202 emitted by the static multiview display200 are used to display the multiview image and may correspond to pixelsof the different views (i.e., view pixels). The directional light beams202 are illustrated as arrows emanating from one or more multiviewpixels 210 in FIG. 8. Also illustrated in FIG. 8 are a first view 14′, asecond view 14″, and a third view 14′″, of a multiview image 16 that maybe provided by the static multiview display 200.

Note that the directional light beams 202 associated with one ofmultiview pixels 210 are either static or quasi-static (i.e., notactively modulated). Instead, the multiview pixels 210 either providethe directional light beams 202 when they are illuminated or do notprovide the directional light beams 202 when they are not illuminated.Further, an intensity of the provided directional light beams 202 alongwith a direction of those directional light beams 202 defines the pixelsof the multiview image 16 being displayed by the static multiviewdisplay 200, according to various embodiments. Further, the displayedviews 14′, 14″, 14′″ within the multiview image 16 are static orquasi-static, according to various embodiments.

The static multiview display 200 illustrated in FIG. 8 comprises anarray of the multiview pixels 210. The multiview pixels 210 of the arrayare configured to provide a plurality of different views of the staticmultiview display 200. According to various embodiments, a multiviewpixel 210 of the array comprises a plurality of diffraction gratings 212configured to diffractively couple out or emit the plurality ofdirectional light beams 202. The plurality of directional light beams202 may have principal angular directions, which correspond to differentviews directions of different views in a set of views of the staticmultiview display 200. Moreover, grating characteristics of thediffraction gratings 212 may be varied or selected based on the radialdirection of incident light beams to diffraction gratings 212, adistance to a light source that provides the incident light beams orboth. In some embodiments, the diffraction gratings 212 and multiviewpixels 210 may be substantially similar to diffraction gratings 130 andmultiview pixel 140, respectively, of the static multiview display 100,described above.

As illustrated in FIG. 8, the static multiview display 200 furthercomprises a light guide 220 configured to guide light. In someembodiments, the light guide 220 may be substantially similar to thelight guide 110 described above with respect to the static multiviewdisplay 100. According to various embodiments, the multiview pixels 210,or more particularly the diffraction gratings 212 of the variousmultiview pixels 210, are configured to scatter or couple out a portionof guided light (or equivalently ‘guided light beams 204’, asillustrated) from the light guide 220 as the plurality of directionallight beams 202 (i.e., the guided light may be the incident light beamsdiscussed above). In particular, the multiview pixels 210 are opticallyconnected to the light guide 220 to scatter or couple out the portion ofthe guided light (i.e., guided light beams 204) by diffractivescattering or diffractive coupling.

In various embodiments, grating characteristics of the diffractiongratings 212 are varied based on or as a function of a radial directionof incident guided light beams 204 at the diffraction gratings 212, adistance between a light source that provides the guided light beams204, or both. In this way, the directional light beams 202 fromdifferent diffraction gratings 212 in a multiview pixel may correspondto pixels of views of a multiview image provided by the static multiviewdisplay 200.

The static multiview display 200 illustrated in FIG. 8 further comprisesa light source 230. The light source 230 may be configured to providethe light to the light guide 220. In particular, the provided light(e.g., illustrated by arrows emanating from the light source 230 in FIG.8) is guided by the light guide 220 as a plurality of guided light beams204. The guided light beams 204 of the guided light beam plurality havedifferent radial directions from one another within the light guide 220,according to various embodiments. In some embodiments, the guided lightbeams 204 are provided with a non-zero propagation angle and, in someembodiments, have a collimation factor to provide a predeterminedangular spread of the guided light beams 204 within the light guide 220,for example. According to some embodiments, the light source 230 may besubstantially similar to one of the light source(s) 120 of the staticmultiview display 100, described above. For example, the light source230 may be butt-coupled to an input edge of the light guide 220. Thelight source 230 may radiate light in a fan-shape or radial pattern toprovide the plurality of guided light beams 204 having the differentradial directions.

In accordance with other embodiments of the principles described herein,a method of static multiview display operation is provided. FIG. 9illustrates a flow chart of a method 300 of static multiview displayoperation in an example, according to an embodiment consistent with theprinciples described herein. The method 300 of static multiview displayoperation may be used to provide one or both display of a staticmultiview image and display of a quasi-static multiview image, accordingto various embodiments.

As illustrated in FIG. 9, the method 300 of static multiview displayoperation comprises guiding 310 the light along the light guide as aplurality of guided light beams having a common point of origin anddifferent radial directions from one another. In particular, a guidedlight beam of the guided light beam plurality has, by definition, adifferent radial direction of propagation from another guided light beamof the guided light beam plurality. Further, each of the guided lightbeams of the guided light beam plurality has, by definition, a commonpoint of origin. The point of origin may be a virtual point of origin(e.g., a point beyond an actual point of origin of the guided lightbeam), in some embodiments. For example, the point of origin may beoutside of the light guide and thus be a virtual point of origin.According to some embodiments, the light guide along which the light isguided 310 as well as the guided light beams that are guided therein maybe substantially similar to the light guide 110 and guided light beams112, respectively, as described above with reference to the staticmultiview display 100.

The method 300 of static multiview display operation illustrated in FIG.9 further comprises emitting 320 a plurality of directional light beamsrepresenting a multiview image using a plurality of diffractiongratings. According to various embodiments, a diffraction grating of thediffraction grating plurality diffractively couples or scatters outlight from the guided light beam plurality as a directional light beamof the directional light beam plurality. Further, the directional lightbeam that is coupled or scattered out has both an intensity and aprincipal angular direction of a corresponding view pixel of themultiview image. In particular, the plurality of directional light beamsproduced by the emitting 320 may have principal angular directionscorresponding to different view pixels in a set of views of themultiview image. Moreover, intensities of directional light beams of thedirectional light beam plurality may correspond to intensities ofvarious view pixels of the multiview image. In some embodiments, each ofthe diffraction gratings produces a single directional light beam in asingle principal angular direction and having a single intensitycorresponding to a particular view pixel in one view of the multiviewimage. In some embodiments, the diffraction grating comprises aplurality of diffraction grating (e.g., sub-gratings). Further, a set ofdiffraction gratings may be arranged as a multiview pixel of the staticmultiview display, in some embodiments.

In various embodiments, the intensity and principal angular direction ofthe emitted 320 directional light beams are controlled by a gratingcharacteristic of the diffraction grating that is based on (i.e., is afunction of) a location of the diffraction grating relative to thecommon origin point. In particular, grating characteristics of theplurality of diffraction gratings may be varied based on, orequivalently may be a function of, radial directions of incident guidedlight beams at the diffraction gratings, a distance from the diffractiongratings to a light source that provides the guided light beams, orboth.

According to some embodiments, the plurality of diffraction gratings maybe substantially similar to the plurality of diffraction gratings 130 ofthe static multiview display 100, described above. Further, in someembodiments, the emitted 320 plurality of directional light beams may besubstantially similar to the plurality of directional light beams 102,also described above. For example, the grating characteristiccontrolling the principal angular direction may comprise one or both ofa grating pitch and a grating orientation of the diffraction grating.Further, an intensity of the directional light beam provided by thediffraction grating and corresponding to an intensity of a correspondingview pixel may be determined by a diffractive coupling efficiency of thediffraction grating. That is, the grating characteristic controlling theintensity may comprise a grating depth of the diffraction grating, asize of the gratings, etc., in some examples.

As illustrated, the method 300 of static multiview display operationfurther comprises providing 330 light to be guided as the plurality ofguided light beams using a light source. In particular, light isprovided to the light guide as the guided light beams having a pluralityof different radial directions of propagation using the light source.According to various embodiments, the light source used in providing 330light is located at a side of the light guide, the light source locationbeing the common origin point of the guided light beam plurality. Insome embodiments, the light source may be substantially similar to thelight source(s) 120 of the static multiview display 100, describedabove. In particular, the light source may be butt-coupled to an edge orside of the light guide. Further, the light source may approximate apoint source representing the common point of origin, in someembodiments.

In some embodiments (not illustrated), the method of static multiviewdisplay operation further comprises animating the multiview image byguiding a first plurality of light guided light beams during a firsttime period and guiding a second plurality of guided light beams duringa second time period during a second period. The first guided light beamplurality may have a common origin point that differs from a commonorigin point of the second guided light beam plurality. For example, thelight source may comprise a plurality of laterally offset light sources,e.g., configured to provide animation, as described above. Animation maycomprise a shift in an apparent location of the multiview image duringthe first and second time periods, according to some embodiments.

In some embodiments, the provided 330 light is substantiallyuncollimated. In other embodiments, the provided 330 light may becollimated (e.g., the light source may comprise a collimator). Invarious embodiments, the provided 330 light may be the guided having thedifferent radial directions at a non-zero propagation angle within thelight guide between surfaces of the light guide. When collimated withinthe light guide, the provided 330 light may be collimated according to acollimation factor to establish a predetermined angular spread of theguided light within the light guide.

Thus, there have been described examples and embodiments of a staticmultiview display and a method of static multiview display operationhaving diffraction gratings configured to provide a plurality ofdirectional light beams representing a static or quasi-static multiviewimage from guided light beams having different radial directions fromone another. It should be understood that the above-described examplesare merely illustrative of some of the many specific examples thatrepresent the principles described herein. Clearly, those skilled in theart can readily devise numerous other arrangements without departingfrom the scope as defined by the following claims.

What is claimed is:
 1. A static multiview display comprising: a lightguide configured to guide light beams; a light source at an inputlocation on the light guide, the light source being configured toprovide within the light guide a plurality of guided light beams havingdifferent radial directions from one another; and a plurality ofdiffraction gratings configured to emit directional light beamsrepresenting a static multiview image, each diffraction grating beingconfigured to provide from a portion of a guided light beam of theguided light beam plurality a directional light beam having an intensityand a principal angular direction corresponding to an intensity and aview direction of a view pixel of the static multiview image.
 2. Thestatic multiview display of claim 1, wherein the input location of thelight source is on a side of the light guide at about a midpoint of theside.
 3. The static multiview display of claim 1, wherein a gratingcharacteristic of the diffraction grating is configured to determine theintensity and the principal angular direction, the gratingcharacteristic being a function of both a location of the diffractiongrating on a surface of the light guide and the input location of thelight source on a side of the light guide.
 4. The static multiviewdisplay of claim 3, wherein the grating characteristic comprises one orboth of a grating pitch of the diffraction grating and a gratingorientation of the diffraction grating, the grating characteristic beingconfigured to determine the principal angular direction of thedirectional light beam provided by the diffraction grating.
 5. Thestatic multiview display of claim 3, wherein the grating characteristiccomprises a grating depth configured to determine the intensity of thedirectional light beam provided by the diffraction grating.
 6. Thestatic multiview display of claim 1, wherein an emission pattern of adirectional light beam of the directional light beam plurality is widerin a direction parallel to a direction of propagation of the guidedlight beam plurality than in a direction perpendicular to the directionof propagation of the guided light beam plurality.
 7. The staticmultiview display of claim 1, wherein the plurality of diffractiongratings are located on a surface of the light guide opposite to a lightbeam emission surface of the light guide.
 8. The static multiviewdisplay of claim 1, further comprising a collimator between the lightsource and the light guide, the collimator being configured to collimatelight emitted by the light source, the plurality of guided light beamscomprising collimated light beams.
 9. The static multiview display ofclaim 1, further comprising another light source at another laterallyoffset input location on the light guide, the other light source beingconfigured to provide another plurality of guided light beams, whereinthe plurality of guided light beams and the other plurality of guidedlight beams have different radial directions from one another, andwherein switching between the light source and the other light source isconfigured to animate the static multiview image, the static multiviewdisplay being a quasi-static multiview display.
 10. The static multiviewdisplay of claim 1, wherein the light guide is transparent to lightpropagating in a direction orthogonal a direction of propagation of aguided light beam of the guided light beam plurality within the lightguide.
 11. A static multiview display comprising: a plate light guide; alight source configured to provide a plurality of guided light beamshaving different radial directions from one another within the platelight guide; and an array of multiview pixels configured to provide aplurality of different views of a static multiview image, a multiviewpixel comprising a plurality of diffraction gratings configured todiffractively couple out light from the guided light beam plurality toprovide directional light beams representing view pixels of themultiview pixel, wherein a principal angular direction of a directionallight beam provided by a diffraction grating of the diffraction gratingplurality is a function of a grating characteristic, the gratingcharacteristic being a function of a relative location of thediffraction grating and the light source.
 12. The static multiviewdisplay of claim 11, wherein the grating characteristic comprises one orboth of a grating pitch and a grating orientation of the diffractiongrating.
 13. The static multiview display of claim 11, wherein anintensity of the directional light beam provided by the diffractiongrating and corresponding to an intensity of a corresponding view pixelis determined by a diffractive coupling efficiency of the diffractiongrating.
 14. The static multiview display of claim 11, wherein the lightsource comprises a first optical emitter laterally offset from a secondoptical emitter along a side of the light guide, the first opticalemitter being configured to provide a first plurality of guided lightbeams and the second optical emitter being configured to provide asecond plurality of guided light beams.
 15. The static multiview displayof claim 11, wherein the light guide is transparent in a directionorthogonal to a direction of propagation of a guided light beam of theguided light beam plurality within the light guide.
 16. A method ofstatic multiview display operation, the method comprising: guiding in alight guide a plurality of guided light beams having a common point oforigin and different radial directions from one another; and emitting aplurality of directional light beams representing a static multiviewimage using a plurality of diffraction gratings, a diffraction gratingof the diffraction grating plurality diffractively coupling out lightfrom the guided light beam plurality as a directional light beam of thedirectional light beam plurality having an intensity and a principalangular direction of a corresponding view pixel of the static multiviewimage, wherein the intensity and principal angular direction of theemitted directional light beam are controlled by a gratingcharacteristic of the diffraction grating that is based on a location ofthe diffraction grating relative to the common origin point.
 17. Themethod of static multiview display operation of claim 16, whereingrating characteristic controlling the principal angular directioncomprises one or both of a grating pitch and a grating orientation ofthe diffraction grating.
 18. The method of static multiview displayoperation of claim 16, wherein the grating characteristic controllingthe intensity comprises a grating depth of the diffraction grating. 19.The method of static multiview display operation of claim 16, furthercomprising providing light to be guided as the plurality of guided lightbeams using a light source, the light source being located at a side ofthe light guide, wherein the light source location is the common originpoint of the guided light beam plurality.
 20. The method of staticmultiview display operation of claim 16, further comprising animatingthe static multiview image by guiding a first plurality of light guidedlight beams during a first time period and guiding a second plurality ofguided light beams during a second time period during a second period,the first guided light beam plurality having a common origin point thatdiffers from a common origin point of the second guided light beamplurality, wherein animation comprises a shift in an apparent locationof the static multiview image during the first and second time periods.